BEIJING -- The Chinese Academy of Sciences (CAS) and the European Space Agency (ESA) have decided their joint space satellite program will focus on an X-ray imaging satellite to study the Earth's magnetosphere, the CAS announced Thursday.

The project, known as SMILE, was selected from 13 proposals and is due to launch in 2021. It plans to study the effects of the Sun on the Earth's environment by creating images of the interactions between solar winds and the Earth's magnetosphere with innovative X-ray and ultraviolet technologies, the CAS said in a statement.

Previously, the ESA contributed to China's Double Star, a similar satellite mission launched in 2003 to focus on the impact of the Sun on the Earth's environment.

SMILE will be the first comprehensive collaboration between China and the ESA with joint efforts in definition, implementation and data utilization, the CAS said, adding that the next step will be a project feasibility study.